acid and bases Flashcards
definition of acids
substance that dissociates or ionises to form h+ ions when dissolved in water
acids + metal
salt and hydrogen
acid + metal carbonate
salt, water, co2
acid + metal oxides/ hydroxides
salt and water
why can strong acids conduct electricity
dissociate in water to form solutions that can conduct electricity due to the presence of mobile ions that act as mobile charge carriers
definition of a base
substance that reacts with an acid to produce salt and water only (+metal oxides & hydroxides)
alkali + acid
salt + wwater
alkali + ammonium salt
ammonia + water + salt
special characteristic of lead sulfate, calcium sulfate, barium sulfate
the initial reaction between lead and acid produces a layer of lead XX which are insoluble in water and non porous, and quickly forms a coating around the metal. the coating prevents lead from further reacting with the acid
reaction between acid and alkali
neutralisation
acids + sodium sulfite
sodium salt + sulfur dioxide + water
test for sulfur dioxide gas
place a strip of filter paper soaked in acidified potassium manganate (VII) solution in gas sample, if present, purple-> colourless
test for ammonia
moist red litmus -> blue
why slaked lime + ammonium nitrate not used at the same time?
ca(oh)2 reacts with nhno3, releasing ammonia gas which escapes from the soil, resulting in a loss of nitrogen from the soil
what is sulfuric acid used for
manufacture of fertilisers, detergents
hydrochloric acid
cleaning agent
use of magnesium oxide
antacid
magnesium hydroxide
toothpaste
strength of acid
extent to which an acid or base dissociates when dissolves in water
ionic compounds as strong electrolytes
when they dissolve in water, the cations and OH- ions break apart from the giant ionic lattice structure to move independently and act as mobile charge carriers
weak base -> bad conductor of electricity?
weak bases only dissociate partially in water, causing them to contain a relatively lower concentration of mobile charge carriers, thus they are weak electrolytes
definition of concentration
amount of substance dissolved in a fixed volume of solution
strength vs concentration
strength - extent of dissociation
concentration - amount of solute dissolved in solvent
dibasic vs monobasic -> concentration of H+
template : Both acids have the same concentration and strength, however, basicity of acid differs. sulphuric acid is a dibasic acid and produces xx concentration of H+ ions, but hbl is a monobasic acid and produces a lower concentration of h+ ions…
ph indicators
methyl orange ( red - yellow, 3-5)
screened methyl orange (pink - green, 3-5)
thymol blue (yellow - blue, 8-10)
phenolphthalein (colourless - pink, 8-10)
types of oxides
basic amphoteric acidic neutral
basic oxides
reacts only with acid to form salt and water
all METAL OXIDES
amphoteric oxides
react with acid and alkalis to form salt and water
LAZ ( Lead oxide, aluminium oxide, zinc oxide)
acidic oxides
react with bases to form salt and water
NON METAL POLYOXIDE
neutral oxides
do not react with an acid or a base
NON METAL MONOXIDE
definition of air pollution
where air contains a high concentration of chemicals that may harm living things or damage non living things
Carbon monoxide is from
the incomplete combustion of petrol in car engines
sulfur dioxide is from
fossil fuels that are burnt, and volcanic eruptions
oxides of nitrogen
where temp is v high, nitrogen combines with oxygen to from nitrogen monoxide
unbury hydrocarbons are from
car exhaust fumes and chemical plants
effects of CO
react with haemoglobin to form carboxyhaemoglobin, which reduces the ability of haemoglobin to transport o2 to rest of body
causes headaches, fatigue, breathing difficulties, death
effects of sulfur dioxide and oxides of nitrogen
irritates eyes and lungs, cause breathing difficulties
high levels lead to bronchitis
react with water in atmosphere to form acid rain, corrode buildings and harm aquatic life & plants
effects of unburnt hydrocarbons
cause cancer
react with nitrogen oxide to form ozone
effect of methane
green house gas, cause global warming
effect of ozone
form photochemical smog, irritate eyes and breathing difficulties
damage crops
formation of acid rain
sulfur dioxide dissolves in water to form sulfurous acid
in the presence of o2 in the air, sulfurous acid is oxidised to sulfuric acid
in the presence of o2 and water, nitrogen dioxide is converted to nitric acid
carbon dioxide dissolves in rainwater to form carbonic acid
ph of acid rain
4 or less
effect of acid rain
react with metals and carbonates, damage metal structures and stone buildings
leaches nutrients from soil, cause plants to wither and die. react with aluminium hydroxide in soil, produce al3+ ions which are toxic to plants
reduce ph value of natural water bodies to below 4, too acidic for aquatic life to survive
catalytic converters
3 steps of redox
1) CO oxidised to CO2
2) Oxides of nitrogen are reduced to nitrogen
3) unburnt hydrocarbons are oxidised to co2 and h2o
flue gas desulfurisation
1) sulfur dioxide passed through plant, react with aq suspension of calcium carbonate to form solid calcium sulfite and co2 gas
2) calcium sulfite further oxidised to calcium sulfate by atmospheric oxygen
[calcium oxide can also be used]
